Same Sex Couples Common in the Wild

As gay couples celebrate their newfound right to marry in
California and opposition groups rally to fight the ruling, many struggle with this
question: Is homosexuality natural?

On this issue, Nature has spoken: Same-sex lovin' is common
in hundreds of species, scientists say.

Roy and Silo, two male chinstrap penguins at New York's
Central Park Zoo, were a couple for about six years, during which they nurtured
a fertilized egg together (given to them by a zookeeper) and raised the young
chick that hatched.

According to University
of Oslo zoologist Petter
Böckman, about 1,500 animal species are known to practice same-sex
coupling, including bears, gorillas, flamingos, owls, salmon and many
others.

If homosexuality is natural in the animal kingdom, then there
is the question of why evolution hasn't eliminated this trait from the gene
pool, since it doesn’t lead to reproduction.

It may simply be for pleasure.

"Not every sexual
act has a reproductive function," said Janet Mann, a biologist at
Georgetown University who studies dolphins (homosexual behavior is very common
in these marine mammals). "That's true of humans and non-humans."

Some scientists have proposed that being gay may serve its
own evolutionary purpose.

"It could be a way that you strengthen bonds — that's
one hypothesis," Mann told LiveScience.
"Another is that it could be practice for heterosexual sex. Bottlenose
dolphin calves mount each other a lot. That might benefit them later
on."

Marlene Zuk, a biologist at the University
of California, Riverside, suggested that gay individuals
contribute to the gene pool of their community by nurturing their relatives’
young without diverting resources by having their own offspring.

"It's a very interesting question as to why anybody
ever cares," Mann said. "There are different theories about why
people find it threatening. Some think it disrupts male bonds, like you're not
playing for the right team. The funny thing is that people say homosexuality is
unnatural, that non-humans don't engage in homosexual behavior, but that's not
true. Then they'll say it's base and animalistic."

Humans' resistance to the idea of homosexuality extends even
to research on the behavior in animals. Scientists who study the topic are often
accused of trying to forward an agenda, and their work can come under greater
scrutiny than that of their colleagues who study other topics, Mann said

"It's kind of a shame because I think that probably is
a reason why people don't look at it more," Mann said. "That's
probably why we haven't gotten further. You would think we'd know more than we
do by now."

Clara has a bachelor's degree in astronomy and physics from Wesleyan University, and a graduate certificate in science writing from the University of California, Santa Cruz. She has written for both Space.com and Live Science.